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          <h1 id="using-renderingcanvas-with-dispengine">Using RenderingCanvas with DispEngine</h1>

<p>The <code>RenderingCanvas</code> is the primary UI component for displaying and interacting with 3D content across different platforms. This section explains how to use it with the <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> to create cross-platform applications.</p>
<h2 id="overview">Overview</h2>
<p>The <code>RenderingCanvas</code> class is available in frameworks:</p>
<ul>
<li><code>Hi.WinForm</code> for Windows Forms applications</li>
<li><code>Hi.Wpf</code> for WPF applications</li>
</ul>
<p>All implementations share a common architecture centered around the <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> class, enabling consistent rendering and interaction across platforms.</p>
<h2 id="core-concept-dispengine-and-idisplayee">Core Concept: DispEngine and IDisplayee</h2>
<p>At the heart of the rendering system is the relationship between <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> and <a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a>:</p>
<ul>
<li><a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a>: The rendering engine that manages the OpenGL context and handles user interaction</li>
<li><a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a>: The interface that defines objects that can be rendered by the DispEngine</li>
</ul>
<p>This relationship is fundamental - <strong>the purpose of <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> is to render <a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a> objects</strong>.</p>
<pre><code class="lang-mermaid">graph TD
    A[IDisplayee Objects] --&gt;|Rendered by| B
    B[DispEngine] &lt;--&gt; C[RenderingCanvas UI Component]
</code></pre>
<h3 id="working-with-idisplayee">Working with IDisplayee</h3>
<p>Objects implementing <a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a> define what gets rendered. Typically, you'll use <a class="xref" href="../../../../../api/Hi.Disp.Drawing.html">Drawing</a> objects or compose multiple IDisplayee objects together:</p>
<pre><code class="lang-csharp">// Create a composite displayee
public class MyCompositeDisplayee : IDisplayee
{
    private List&lt;IDisplayee&gt; _displayees = new List&lt;IDisplayee&gt;();
    
    public MyCompositeDisplayee()
    {
        // Add various displayees
        _displayees.Add(new AxesDisplayee());
        _displayees.Add(new ModelDisplayee());
    }
    
    public void Display(Bind bind)
    {
        // Render all contained displayees
        foreach (var displayee in _displayees)
        {
            displayee.Display(bind);
        }
    }
    
    public void ExpandToBox3d(Box3d box)
    {
        // Update bounding box based on all displayees
        foreach (var displayee in _displayees)
        {
            displayee.ExpandToBox3d(box);
        }
    }
}
</code></pre>
<p>For more detailed information on creating displayees with <a class="xref" href="../../../../../api/Hi.Disp.Drawing.html">Drawing</a>, see the <a href="../drawing/index.html">Drawing</a> section.</p>
<h2 id="basic-usage">Basic Usage</h2>
<h3 id="apply-hiwinform">Apply Hi.WinForm</h3>
<pre><code class="lang-csharp">// Create a new instance with displayee objects
using Hi.WinForm.Disp;

// Create displayee object
var displayee = new MyCompositeDisplayee();

// Initialize canvas with the displayee
var canvas = new RenderingCanvas(displayee);

// Access the DispEngine for direct manipulation
DispEngine engine = canvas.DispEngine;

// Add to a form
myForm.Controls.Add(canvas);
</code></pre>
<h3 id="apply-hiwpf">Apply Hi.WPF</h3>
<pre><code class="lang-csharp">// Create a new instance
using Hi.Wpf.Disp;

// Create displayee object
var displayee = new MyCompositeDisplayee();

// Initialize the canvas
var canvas = new RenderingCanvas();

// Set displayee objects through the DispEngine
canvas.DispEngine.Displayee = displayee;

// Add to a container
myGrid.Children.Add(canvas);
</code></pre>
<h2 id="switching-displayees-at-runtime">Switching Displayees at Runtime</h2>
<p>You can dynamically change what's being displayed:</p>
<pre><code class="lang-csharp">// Switch to a different displayee
renderingCanvas.DispEngine.Displayee = alternativeDisplayee;

// Or update a DispList
var displayList = new DispList();
if (showModel) displayList.Add(modelDisplayee);
if (showGrid) displayList.Add(gridDisplayee);
renderingCanvas.DispEngine.Displayee = displayList;
</code></pre>
<h2 id="key-features-of-dispengine">Key Features of DispEngine</h2>
<p>The <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> provides cross-platform support for:</p>
<ul>
<li>Handles buffer swapping and image generation</li>
<li>Mouse/pointer events</li>
<li>Keyboard navigation</li>
<li>Touch gestures</li>
<li>Zoom, pan, and rotate operations</li>
<li>Resize and Visibility changed.</li>
<li>Camera positioning and orientation</li>
<li>Standard views (front, top, isometric, etc.)</li>
<li>Renders <a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a> implementations</li>
</ul>
<h2 id="touch-and-gesture-support">Touch and Gesture Support</h2>
<p>The <a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a> centralizes touch handling across all platforms with a unified API that supports:</p>
<ul>
<li>Single-finger pan</li>
<li>Two-finger rotate and scale</li>
<li>Multi-finger specialized operations</li>
</ul>
<p>The touch API is designed to be simple for UI implementations to use. Platform-specific UI components only need to capture touch events and forward them to the DispEngine.</p>
<h2 id="common-operations">Common Operations</h2>
<pre><code class="lang-csharp">// Accessing DispEngine (works on all platforms)
var engine = renderingCanvas.DispEngine;

// Set to standard views
engine.SetViewToHomeView();
engine.SetViewToFrontView();

// Manual camera manipulation
engine.Translate(dx, dy);
engine.Rotate(deltaX, deltaY);

// Resize handling
engine.Resize(width, height);
</code></pre>
<h2 id="implementation-details">Implementation Details</h2>
<p>For detailed implementation information, including:</p>
<ul>
<li>Full source code examples</li>
<li>Implementation details for each platform</li>
<li>Advanced touch handling</li>
<li>Custom implementation guidance</li>
</ul>
<p>See the <a href="custom-implementation.html">Building Your Own RenderingCanvas</a> guide.</p>
<h2 id="see-also">See Also</h2>
<ul>
<li><a class="xref" href="../../../../../api/Hi.Disp.DispEngine.html">DispEngine</a></li>
<li><a class="xref" href="../../../../../api/Hi.Disp.IDisplayee.html">IDisplayee</a></li>
<li><a class="xref" href="../../../../../api/Hi.Disp.DispList.html">DispList</a></li>
<li><a class="xref" href="../../../../../api/Hi.Disp.Drawing.html">Drawing</a></li>
<li><a href="custom-implementation.html">Building Your Own RenderingCanvas</a></li>
</ul>

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